In 1221, Genghiz, Great Khan of the Mongols, ordered an armed reconnaissance expedition into Russia commanded by Sübodei Bahadur and Jebei Noyon 'The Arrow'. The overwhelming Mongol victory over Prince Mstislav 'the Daring' of Galicia along with his Russian and Kipchaq allies at the battle of the Kalka River was one of the most significant events in Russian history. For the Mongols it may have been merely a reconnaissance in force, but for the Russians and the rest of Christian Eastern Europe it was a disaster, opening up vast regions to subsequent Mongol conquest. The final cataclysm had to wait a few years, delayed by internal Mongol politics and events elsewhere. In the meantime the Russians were incapable of strengthening their defences enough to withstand the second and third waves. As a result Russia fell under what historians call 'the Mongol yoke' for several centuries. Even today some still blame defeat at the Kalka River and the subsequent Mongol occupation for Russia's supposed isolation and separation from the mainstream of European history. Furthermore this campaign was the first in a series undertaken by victorious Mongol forces in Eastern and Central Europe. The battle was, in the true sense, a turning point in European history. It was also interesting from a military-historical point of view, pitting an essentially European army plus its Turkish steppe allies against a Mongol army that already drew upon the heritage of Chinese warfare. It was a battle in the open steppe grasslands in which Mongol horse-archery tactics reigned supreme. But it was also the culmination of a campaign in which the Russians made considerable use of their own highly developed system of river transportation of armies and supplies. They also used riverside locations as strategic military bases. It involved Black Sea fleets, field fortifications, wide sweeping manoeuvres particularly by the Mongols, and close cooperation between Christian Russians and already substantially Islamic Kipchaq Turks. Text by David Nicolle with illustrations by Victor Korolkov.